How exotic plants integrate into pollination networks

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1. There is increasing world-wide concern about the impact of the introduction of exotic species on
ecological communities. Since many exotic plants depend on native pollinators to successfully establish,
it is of paramount importance that we understand precisely how exotic species integrate into
existing plant–pollinator communities.
2. In this manuscript, we have studied a global data base of empirical pollination networks to determine
whether community, network, species or interaction characteristics can help identify invaded
communities.
3. We found that a limited number of community and network properties showed significant differences
across the empirical data sets – namely networks with exotic plants present are characterized
by greater total, plant and pollinator richness, as well as higher values of relative nestedness.
4. We also observed significant differences in terms of the pollinators that interact with the exotic
plants. In particular, we found that specialist pollinators that are also weak contributors to community
nestedness are far more likely to interact with exotic plants than would be expected by chance alone.
5. Synthesis. By virtue of their interactions, it appears that exotic plants may provide a key service
to a community’s specialist pollinators as well as fill otherwise vacant ‘coevolutionary niches’.